Test Technologies Contributing to Electrification - 2. Driving Simulator Test Technologies for Establishing Unique Performances of Electric VehiclesFig. 7 Elements of accelerationFig. 8 Method of evaluating feeling of growthFig. 9 Sensory evaluation results3.2 e-4ORCE acceleration and deceleration control 42Fig. 10 AURA NISMOdevelopment (1)results indicates that the feeling of acceleration was improved, which demonstrates that a parameter study evaluation with the DS is also possible. The “growth” of each element is explained in this section.The decrease in acceleration after peak acceleration in relation to the accelerator opening was investigated to create a feeling of acceleration growth (Fig. 8). The smaller the drop in acceleration after the peak acceleration, the stronger the feeling of acceleration with more growth. However, peak acceleration was difficult to maintain because of the upper limit on the output. We attempted to reproduce the feeling of acceleration growth by controlling the drop in acceleration. The Y-parallel rails of the DS were used in the test to evaluate front/rear acceleration, which enabled an approximately 3-second evaluation for an acceleration of 0.3 G. The change could be sufficiently felt, although the evaluation was only conducted for a brief time because the actual setup also included a deceleration section. As presented in Fig. 8, the acceleration dropped after the peak acceleration was varied to score the performance in the test. The scores for different drops in acceleration varied at speeds near the start and at medium speed. Acceleration with a feeling of growth could be felt at an acceleration reduction rate of 0.04 G/s or lower for low speeds and at 0.025 G/s or lower for a medium speed range (Fig. 9).AURA NISMO was specially tuned based on these results to provide the “NISMO” mode, which allows drivers to enjoy the feeling of powerful acceleration with growth that is unique to NISMO.Approximately 130 specifications were evaluated in the three-day test using the DS. This is equivalent to a six-week test for an actual vehicle. The results indicate that analyzing the data in a short time would have been impossible without using the DS, which can perform stable evaluations.The design methodology includes the passenger sensation required for Nissan's automobile development in addition to quantitative performance evaluation. Many laboratories have reported on the prediction of vehicle and system behavior using CAE simulation; however, reports on performance prediction and design that include human subjective evaluation remain limited. The prediction of human senses is required for subjective human evaluations, which leaves a large part of its modeling unknown. Although performance design can be evaluated based on past data and experience, completely new behavior and performance can only be evaluated by testing an actual vehicle. However, building a large number of prototype vehicles is difficult.Human subjective evaluation is added to predict not only the design and performance in CAE simulations, but also the sensory experience of passengers, which is difficult to include in the development of e-4ORCE control. Comprehensive tests, which include sensory tests, were efficiently developed using a DS without prototype vehicles. A performance design methodology incorporating subjective human evaluation and the influence of passengers is presented.The performance design methodology using a DS, human body simulation, and vehicle motion simulation is presented in Fig. 11. Using the DS, the vehicle state quantities that can be changed by this new electric AWD were studied to perform a subjective sensitivity analysis for each state quantity. The parameters that most affect human senses were determined based on subjective sensitivity analysis results for clarifying the mechanism and incorporating them into quantitative index values
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